I still see some misunderstanding in the posts and since engineering jargon confuses people and is not appropriate for the forum I feel obligated to do a better job explaining in terms of concept (no fancy words). This can be done by comparing two imaginary boats that are identical in their shape, volumes and rig geometry. Boat A is the stock Marstrom Tornado built of S-glass and aluminum spars. Boat B is a tornado made out of imaginary stuff that is infinately strong and stiff so it dosen't weigh anything. Say we want to correct boat B so it can race fairly with boat A. One approach might be to fit a single large weight correction on the centerline just aft the beam of boat B and a few inches above the designed waterline. So now boat A and B float on the same waterline and if we pull them through still water they have the same resistance. But are they fairly handicapped? Next boat A is sailed against boat B in a seaway and boat B beats the crap out of boat A. Why? What's the difference? Boat B has smaller radius of gyration with respect to it's three rotational axes: pitch, roll, and yaw (this is the technically correct term in continuum mechanics in this country). The concept here is fundamental to boat design. It is expressed by the sailors intuition to keep weight out of the ends and as low as possible.

Kevin